Solvent refining



Oct. 31', 1939. l.. A. CLARKE SOLVENT REFINING Louis A. CLARKE INVENTOR .Ill

ATTORN EY Patented of.31,1939 i 2,178,321

v'Uuirlao STAT-s PATENT ornes y n Louis A. Clarke,v Fishkill, N. Y., assignor to The Texas Company, New York,.N. Y., a corpora, tion of Delaware Application Aprile, 1937, serial No. 134.465

2 Claims. (Cl. 19e-13) This invention relates to refining hydrocarbon tillate va mixture having the vfollowing composi- -oil by solvent extraction. tion:

The inventionl contemplates a method .of re- Table 1 lining lubricating oil stocks of different charac- Per cent ,5, teristics by solvent extraction in a related operv by volume 6' ation for the production of lubricating oil prod- Phenol -40 Vucts of desired characteristics. The invention Parachlorphenol -55 has reference to thesolvent extraction of lubri- Orthochlorphenol 20`50 cating oil fractions derived from different crude Dichlorphenol 0-3 10 grade and a 10W grade stock in a related operv ation. The invention concerns, for example, the rethis` fining of residual lubricating oil fractions derived 5 from different crude sources and by extraction with a solvent that is capable of effectively 'extracting asphaltic as well'as low viscosity index l constituents from the oil. The method of my invention involves subject- 0 ing a high grade lubricating oil stock to extraction in a primary stage to produce a rainate paraand orthomonochlorphenol containing about 50`;.to 75% of the paracompound pro-e` 20 vides a satisfactory mixture. I

A chlorinated phenol mixturev which we have found particularly, effective has the following heavy extract oil of relatively low viscosityindex. 0143110CfllOlflJhell01 31011@ has OO high S0111- The extraction may be e'egted with the Same bility fOIi/he COHSUSIIS Oflllbl'iCalJllg Oil. O11 type of selective solvent in both stages. -By sethe other hand, the para Compound Sololes at leotive solvent I contemplate a solvent having temperatures around room temperature. A mixselective action as between low and high visture of the two in the proportions above indicated cosity index constituents of the oil, y such as DOSSSSSES many adVaItgeS aS refining Solvent furfural, phenol, 'nitrobenzena etc. A solvent for hydrocarbon oil which Cannot be'SeCured by which I have found to be particularly suitable the use 0f the' isomers separately. One advan- 40 for this purpose comprises a chlorinated phenol y tageof a chlorphenol mixture, such as above demixture obtained byjchlorinating crude phenol. scribed, resides in its ability to extract `resinous Achlorinated phenol mixture such as I conasphaltic constituents iromfthe oil'to a very template is obtained by chlorinating crude` high degree. phenol under conditions such that at least 60% This type of solvent is particularly eflicient in 451 of the phenol is chlorinated to produce a mixthe case of residual lubr1cating `oil stocks from ture comprising mainly a mixture of orthoand theA standpoint of producing lubricating oil thereparamonochlorphenol which may contain someK from having a relatively light color and a relaunreacted phenol as well as a small amount of tively'low residualcarbon content. .Y :lichlorphenol. This chlorinated mixturel is In order to illustrate the process of my inmeatedwith suicient alkali to remove hydrogen vention as applied to the rening of residual lu- :hloride formed during the chlorination, and bricating oil stocks, reference Will now be made titer removal ofthe hydrogen chloride the mixto 'the accompanying drawing showing` a iiow ure is distilled to a temperature of around 220 diagram ofthe process. I. at atmospheric pressure to remove as a dis- A high grade resduallubricating oil fraction,`

SUT

such as derived from mixed with propane and conducted to a settler I. The propane is mixed with the oil in the ratio of about three parts of propane to one part of Mid-Continent crude, is

oil, or sufficient so as to cause precipitation of hard asphaltic constituents, and which is brought settler at a temperature of around 120 F. The hard asphaltic constituents are drawn oi from the bottom of the settler, while the solution of oil in propane is drawn off from the top of the settler and conducted 4to the lower portion of a primary extractor 2.

The primary extractor 2 may comprise a vertical column packed with suitable contacting material, such as Raschig rings, and adapted to eiect countercurrent contact between oil and extraction solvent.

The extraction solvent, having the composition set forth in Table 2 above, is introduced to the upper portion of the extractor 2 in the proportion of about two to four parts of solvent to one part of undiluted oil. The extractor 2 is maintained at a temperature of around to 120 F.

The `raffinate phase accumulating in the upper portion of the extractor 2 under these conditions will comprise oil of relatively high viscosity index and suitable, for example, as an airplane oil. This primary raiiinate phase is withdrawn and the solvent recovered therefrom.

The primary extract phase will contain oil of lower viscosity index, a substantial proportion of which is of intermediate character, as a lubricating oil product. This oil is dissolved in the main body of the extraction solvent, and by the method of my invention is introduced to the mid-point oi a secondary extractor 3.

Fresh lchlorphenol mixture is introduced to the upper portion of this secondary extractor, while a lower grade oi residual lubricating oil stock is introduced to the lower portion of the extractor 3.

This lower grade stock advantageously comprises a residual lubricating oil fraction derived from a Coastal type of crude, or from a crude, such as Manvel crude. This low grade residual fraction is also mixed with propane in the proportion of about five or six parts of propane to one part of oil, and the mixture introduced to a settler 4 wherein precipitation of hard asphaltic constituents is brought about.

TheV hard asphaltic matter so precipitated is withdrawn as indicated while the remaining solution of oil and propane is introduced to the lower portion of the extractor 3, as previously indicated.

This low grade residuum is thus brought into countercurrent contact with the extraction solvent in the presence of the primary extract phase drawn off from the primary extractor 2. The extraction solvent is introduced to the upper portion of the secondary extractor 3 in the ratio of about two to four parts of solvent to one part of low grade oil introduced to the bottom of the extractor. The extraction temperature maintained within the secondary extractor 3 may be the same as that maintained in the primary extractor, or, if desired, may be some lower temperature.

'I'he secondary raffinate phase drawn ofi from the top of the secondary extractor 3 comprises oil of intermediate character and includes a substantial amount of the oil contained in the primary extract phase.

The secondary extract phase comprises relatively low grade oil and those asphaltic constituents particularly of a resinous character which were not removed in the settlers l and 4.

These secondary phases are separately withdrawn and the solvent removed therefrom.

Thus, a feature of my invention involves the extraction of a low grade lubricating oil stock with a selective solvent in the presence of lubrieating oil constituents extracted from a relatively high grade of lubricating oil stock.

Introduction of the primary extract phase to the secondary extraction tower permits utilizing the large amount of solvent retained in the primary extract phase as a defining agent in the secondary extraction. It also eliminates the necessity for separately stripping the solvent from the primary extract phase; that is, there is only one nal extract phase produced which requires stripping to remove the solvent.

A further feature of the process resides in the flexibility of operation, permitting the obtaining of products of different characteristics.

Also, where a chlorphenol mixture oi the ccmposition disclosed is used, there is no necessity for subjecting the charge stock to a separate treatment for the removal of soft asphaltic constituents. Thus, it is unnecessary, after the hard asphaltic constituents have been removed, to subject ,the solution of oil in propane to different temperature conditions and different dilution ratios in order to effect removal of the soit or resinous asphaltic constituents, as would otherwise be the case. These soft asphaltic constituents are removed by the chlorphenol mixture as part of the final extract phase.

`An object of the invention is to extract socalled paraffin-base or Mid-Continent oil in one stage, `extract so-called naphthene-base or Coastal oil in the second stage, and pass the extract from the rst stage to the second stage. In this way, a specially high grade lubricating oil, such as an airplane oil, is obtained from the first stage without sacrificing yield or losing val uable lubricating oil constituents of somewhat lower grade in the extract. At the same time, a high yield of medium grade or industrial oil is obtained from the second stage, the character of this oil being superior on a yield basis to that which it is possible to obtain from a naphthene-base crude alone.

Obviously, many modifications and variations of the invention, as hereinbeiiore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be made as are indicated in the appended claims.

l'. claim:

1. The method of solvent refining high grade parailin base lubricating oil and low grade naphthene base lubricating oil derived from diiferent crude sources comprising extracting the paraffin base lubricating oil stock with a selective solvent comprising a chlorphenol mixtureY containing about 15% phenol, 31% orthochlorphenol, 51% parachlorphenol, and 3% dichlorphenol, forming a primary raiiinate phase comprising highly parainic oil and a primary extract phase rich in solvent and relatively parainic constituents of the oil, separating the two phases, flowing the primary extract phase through a separate extraction Zone countercurrently to said naphthene base lubricating oil and in the presence of fresh solvent, forming a secondary extract phase containing low viscosity index oil, ane" a secondary rainate phase comprising oil oi relatively higher viscosity index, and separating the two phases.

2. The method of solvent-refining high grad 4extracting the partially deasphalted paran base primary extract phase through a separate extraction zone countercurrently to said naphthene LOUIS A. CLARKE. 

